bisecting fixing commit since c4ff839de17f38b0ae0f8983b5c5186f8a389238 building syzkaller on a57db36fe48aa500618c2eac3b38c27afe6d290f testing commit c4ff839de17f38b0ae0f8983b5c5186f8a389238 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 54cde6d9374795d2316fe89ed381ecac8ef58a8fb973a50f1d6a07d389088f53 all runs: crashed: general protection fault in hsr_dev_change_mtu testing current HEAD 6db10b4d5efdc38ff06dfdde28dc5477f754b0bd testing commit 6db10b4d5efdc38ff06dfdde28dc5477f754b0bd compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 99b066ff58c6710a34322dd7b730ae05bddad90c60131f8fbcaa25ec6330d1a2 all runs: crashed: general protection fault in hsr_dev_change_mtu revisions tested: 2, total time: 28m22.135334997s (build: 20m56.44959326s, test: 7m0.688981264s) the crash still happens on HEAD commit msg: Linux 4.19.209 crash: general protection fault in hsr_dev_change_mtu netlink: 'syz-executor.0': attribute type 10 has an invalid length. bond0: enslaved VLAN challenged slave hsr4. Adding VLANs will be blocked as long as hsr4 is part of bond bond0 bond0: The slave device specified does not support setting the MAC address kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 9960 Comm: syz-executor.0 Not tainted 4.19.209-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:hsr_dev_change_mtu+0x87/0xb0 net/hsr/hsr_device.c:149 Code: 02 00 00 31 c0 5b 41 5c 41 5d 41 5e 5d c3 e8 c0 49 11 fa eb e7 49 8d 7e 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 1c 49 8b 7e 10 ba 06 00 00 00 48 c7 c6 00 21 ff 88 RSP: 0018:ffff88808d466970 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff8880977e6200 RCX: 1ffff1101347710f RDX: 0000000000000002 RSI: 0000000000000002 RDI: 0000000000000010 RBP: ffff88808d466990 R08: 0000000000000000 R09: ffffed101746455a R10: ffffed101746455a R11: ffff8880ba322ad3 R12: ffff8880977e6d00 R13: 00000000000005dc R14: 0000000000000000 R15: ffffffff88ff22e0 FS: 00007f8c770ba700(0000) GS:ffff8880ba200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f993eade000 CR3: 00000000b4d59000 CR4: 00000000003406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __dev_set_mtu net/core/dev.c:7763 [inline] dev_set_mtu_ext+0x257/0x530 net/core/dev.c:7816 dev_set_mtu+0x87/0xe0 net/core/dev.c:7840 bond_enslave+0x695/0x4c60 drivers/net/bonding/bond_main.c:1530 do_set_master net/core/rtnetlink.c:2321 [inline] do_set_master+0x171/0x200 net/core/rtnetlink.c:2295 do_setlink+0x94c/0x2ec0 net/core/rtnetlink.c:2455 rtnl_newlink+0x975/0x1360 net/core/rtnetlink.c:3077 rtnetlink_rcv_msg+0x34f/0x950 net/core/rtnetlink.c:4782 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x660 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x667/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 ___sys_sendmsg+0x647/0x950 net/socket.c:2227 __sys_sendmsg+0xd9/0x180 net/socket.c:2265 __do_sys_sendmsg net/socket.c:2274 [inline] __se_sys_sendmsg net/socket.c:2272 [inline] __x64_sys_sendmsg+0x73/0xb0 net/socket.c:2272 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x465b09 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8c770ba188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465b09 RDX: 0000000000000000 RSI: 0000000020000600 RDI: 0000000000000005 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008 R13: 00007fff0249fddf R14: 00007f8c770ba300 R15: 0000000000022000 Modules linked in: ---[ end trace 4280b1931abc82b1 ]--- RIP: 0010:hsr_dev_change_mtu+0x87/0xb0 net/hsr/hsr_device.c:149 Code: 02 00 00 31 c0 5b 41 5c 41 5d 41 5e 5d c3 e8 c0 49 11 fa eb e7 49 8d 7e 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 1c 49 8b 7e 10 ba 06 00 00 00 48 c7 c6 00 21 ff 88 RSP: 0018:ffff88808d466970 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff8880977e6200 RCX: 1ffff1101347710f RDX: 0000000000000002 RSI: 0000000000000002 RDI: 0000000000000010 RBP: ffff88808d466990 R08: 0000000000000000 R09: ffffed101746455a R10: ffffed101746455a R11: ffff8880ba322ad3 R12: ffff8880977e6d00 R13: 00000000000005dc R14: 0000000000000000 R15: ffffffff88ff22e0 FS: 00007f8c770ba700(0000) GS:ffff8880ba300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1fde802718 CR3: 00000000b4d59000 CR4: 00000000003406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 02 00 add (%rax),%al 2: 00 31 add %dh,(%rcx) 4: c0 5b 41 5c rcrb $0x5c,0x41(%rbx) 8: 41 5d pop %r13 a: 41 5e pop %r14 c: 5d pop %rbp d: c3 retq e: e8 c0 49 11 fa callq 0xfa1149d3 13: eb e7 jmp 0xfffffffc 15: 49 8d 7e 10 lea 0x10(%r14),%rdi 19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 20: fc ff df 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2e: 75 1c jne 0x4c 30: 49 8b 7e 10 mov 0x10(%r14),%rdi 34: ba 06 00 00 00 mov $0x6,%edx 39: 48 c7 c6 00 21 ff 88 mov $0xffffffff88ff2100,%rsi